Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
  • Effective date searches are available only for US area codes. Our sources for non-US NPA-NXX data do not provide this information.
  • If you want to search an entire area code regardless of activity, leave both the next and past days fields set to zero.

Switch: CHCGILWUQMD

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
312-761 A Chicago Zone 01-Calumet IL 148J TELENGY LLC 358      
312-761 0 Chicago Zone 01-Calumet IL 148J TELENGY LLC 358   2018-07-09   
773-541 4 Chicago Zone 02-Edgewater IL 148J TELENGY LLC 358   2020-02-29   

Last updated: Thu, 16 Oct 2025 03:04:18 UTC

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